from sys import stdin, stdout

def problema(a):
    if a >= 30:
        return "Yes"
    else:
        return "No"

def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    stdout.write(problema(a))
main() from sys import stdin, stdout def problema(a):
    if a >= 30:
        return "Yes"
    else:
        return "No" problema if a >= 30:
        return "Yes"
    else:
        return "No" a >= 30 a 30 return "Yes" "Yes" return "No" "No" a a def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    stdout.write(problema(a)) main line = stdin.readline() line stdin.readline() stdin.readline stdin readline parts = line.split() parts line.split() line.split line split a = int(parts[0]) a int(parts[0]) int parts[0] parts 0 stdout.write(problema(a)) stdout.write stdout write problema(a) problema a main() main def problema(a):
    if a >= 30:
        return "Yes"
    else:
        return "No" def problema(a):
    if a >= 30:
        return "Yes"
    else:
        return "No" problema def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    stdout.write(problema(a)) def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    stdout.write(problema(a)) main
from sys import stdin, stdout

def problema(a):
    if a >= 30:
        return "Yes"
    else:
        return "No"

def main():
    line = stdin.readline()
    parts = line.split()
    a = int(parts[0])
    stdout.write(problema(a))
main()